I haven't had a surface before, but I heard of them because my step daughter bought herself a surface 2, I didn't know much (anything) about them before that ( I have desktop, old large laptop and a Nexus 7 tablet), I wasn't even aware that there was a pro-version of the surface running full windows until I saw one in a shop and played with it (pro 2) I was very impressed by the device but in that form-factor (screen size mainly) I wouldn't even have considered it as a purchase at the price, however when I heard of the Pro 3 and the specs before release it piqued my interest as the screen aspect and size (plus the new hinge) lends itself much more to replacing my aging laptop, which would be it's main duty, but also for occasional note taking tasks in portrait mode as a tablet, or ebook reading etc. My Nexus 7 is a brilliant device but for some tasks a larger screen is preferable, even on a tablet.
I can see this version definitely having a MUCH wider appeal as it's more accessible both as a laptop AND tablet. I get the impression that few people use the Pro 2 as a tablet device in portrait mode because the screen aspect ratio doesn't really lend itself so much to it. I simply can't wait to get mine, for me anyway MSFT made a very good decision to go for the bigger screen as well I wouldn't be a customer without it.